A standard lathe typically has either a multi-jaw chuck (typically, a 3, 4, or 6 jaw chuck) threaded or cam locked to the spindle for holding a large tool or has a collet holder threaded or cam locked to the spindle for holding a smaller tool with a smooth shank. Chucks and collet holders can be interchanged; however, the chucks can weigh one hundred pounds or more. Thus, interchanging various chucks or interchanging a chuck with a collet holder takes quite of bit of time and manpower.
Thus, it can be seen that needs exist for an adapter to a multi-jaw chuck that can hold collets without removing the chuck and installing a collet holder directly to the headstock.